title: Design and development of a fascioperiosteal flap for use in experimental cranial surgery in a porcine model.
abstract: As part of an ongoing program of research on reconstructive techniques applicable to the growing craniofacial skeleton, this study aimed to characterize a pedicled fasciocutaneous flap on the scalp of a porcine model. Twelve juvenile Yorkshire white pigs were used. The anatomy of the porcine scalp was determined by fresh cadaveric dissection, radiocontrast dye injection, and resin casting of the vascular supply. No direct analogue of the human superficial temporal artery, the key to the superficial and deep temporal fascial flaps in humans, could be demonstrated in the pig. Thus, a fascioperiosteal flap, pedicled on an occipital leash of vessels, was designed. After a 14-day surgical delay, this flap, which covered the entire cranial width, from the nuchal crest to the glabella (7-10 cm long x 3-4 cm wide), could be elevated and split into a periosteal and a fascial layer. A cartilage construct placed between these layers could be kept alive for 4 weeks with no evidence of necrosis. The flap would allow mobilization of the construct to distant sites on the head and neck. An extensive literature survey showed a dearth of suitable cranial flap options in animal models. Accordingly, the pig cranium was examined with a view to finding a fascial flap analogous to the human temporoparietal flap, suitable for use in ear reconstruction. Cadaver dissections of the pig scalp, examining both the fascial layers and blood supply, were performed in three pigs; in an additional three pigs, the vascular supply to the scalp and cranium was injected with a radiocontrast gel, and, after dissecting suitable flaps, x-ray exposure was used to demonstrate the microvascular supply of these flaps. In an additional two pigs, the cranial vascular tree was filled with a plastic resin, and the soft tissues were then removed by thermal and chemical digestion. Finally, a group of three pigs were used to test the functional efficacy of a bilayered, occipitally based fascioperiosteal flap, whose design evolved from the foregoing work. Fluoresceine and disulphine blue were used to demonstrate the vascularity of these flaps before and after a surgical delay procedure. Function of these flaps, as carriers of a reconstructive construct, was shown by implanting autologous cartilage for 3 weeks and then demonstrating complete survival of the implant by fine section and histology. No clinically useful equivalent of the superficial temporal artery in humans could be identified in pigs, thus rendering the porcine superficial temporal artery flap of little use. However, a useful flap, comprising the pericranium and the subgaleal fascia, based on the occipital vasculature, could be raised with relative ease.
authors.affiliation: Division of Plastic Surgery, Hospital for Sick Children, University of Toronto, Ontario, Canada.
authors.forename: T
authors.initials: T
authors.lastname: de Chalain
authors.forename: J H
authors.initials: JH
authors.lastname: Phillips
mesh_terms: D000818:Animals; D002356:Cartilage / Q000637:transplantation; D003399:Craniotomy; D004195:Disease Models, Animal; D005205:Fascia / Q000098:blood supply / Q000637:transplantation*; D006085:Graft Survival; D006801:Humans; D010521:Periosteum / Q000098:blood supply / Q000637:transplantation*; D012535:Scalp / Q000098:blood supply / Q000637:transplantation*; D013524:Surgical Flaps; D013552:Swine; D013699:Temporal Arteries / Q000033:anatomy & histology